Polyfluoroalkylphosphonic acid esters are widely used as starting materials for the synthesis of mold-releasing agents. Compounds having a C8-C12 perfluoroalkyl group are most likely to develop mold release performance when used as mold-releasing agents. In particular, C8 telomer compounds of the formula:CF3(CF2)7CH2CH P(O)(OC2H5)2 are preferably used for this kind of application (see Patent Documents 1 to 4).
Incidentally, it is reported that telomer compounds having a C8-C12 perfluoroalkyl group are biologically degraded in the environment and converted to compounds having relatively high bioaccumulation and environmental concentration, causing concerns for exposure during treatment processes, and for release or diffusion from waste, treated substrates, etc., into the environment. Moreover, compounds having a perfluoroalkyl group containing 14 or more carbon atoms are very difficult to handle because of their physical and chemical properties, and hence, such compounds are rarely used in practice.
Furthermore, as for telomer compounds having a perfluoroalkyl group containing 8 or more carbon atoms, generation and incorporation of perfluorooctanoic acids with high bioaccumulation potential is unavoidable during the production of these compounds. For these reasons, companies that produce such telomer compounds have retreated from the production of the compounds or promoted the use of alternative compounds having a perfluoroalkyl group containing 6 or less carbon atoms.
However, compounds having a perfluoroalkyl group containing 6 or less carbon atoms cause a significant decrease in orientation on the surface of a treated substrate, and the melting point, glass transition point (Tg), etc., of the compounds are markedly lower than those of C8 compounds. Accordingly, the compounds are highly influenced by their environmental conditions, such as temperature, humidity, stress, and contact with organic solvents. Consequently, the desired performance cannot be sufficiently achieved, and durability and other properties are affected.